This invention relates to glass compositions, and in particular to such compositions which are soluble in water or other polar solvents. Furthermore, this invention relates to glass-polymer alloys formed using these particular compositions.
Surgical devices such as clips and staples made from various metals, such as stainless steel and titanium, are becoming more frequently used in the medical profession as substitutes for and/or complements to surgical sutures and ligatures. In some surgical procedures, the staples are used internally and as thus employed are not removed, but are left inside the patient. The human (and animal) body has ways of isolating such foreign objects left inside a patient so not be to be detrimental. However, surgeons would prefer to use absorbable staples that would dissolve at least to some extent after their function during wound healing. Such dissolution would enable the body to more easily isolate the foreign object.
It has been proposed to produce staples from synthetic absorbable polymers. For instance, many patents that relate to synthetic polymers disclose surgical staples as one, of many, proposed uses. However, thus far surgical staples made from synthetic absorbable polymers have had limited applications in the medical profession because the polymers have yet to achieve the requisite combination of properties needed for more substantial use. Specifically, a staple made from an absorbable polymer must have sufficient stiffness to penetrate tissue; it must retain sufficient strength to perform its function during the wound healing process; and it must then eventually be absorbed by the body. It has proven to be especially difficult to achieve this necessary combination of properties; specifically, the bioabsorbable synthetic polymers, by themselves, have only sufficient stiffness to be used in applications other than those requiring miniature staples, clips or fasteners.
Therefore, efforts were directed towards developing materials which could be used to reinforce existing bioabsorbable synthetic polymers, thus resulting in a composite which possesses sufficient stiffness and absorbability. Illustrative is U.S. Pat. No. 4,604,097 (Graves Jr. et al.) which discloses a glass fiber for use in the area of medical implants, and particularly as a reinforcement for bioabsorbable polymeric orthopedic and dental implants. Also illustrative is U.S. Pat. No. 4,612,923 (Kronenthal) which describes a surgical device, a ligating clip being the preferred device, fabricated from a synthetic absorbable polymer containing an absorbable glass filler. One further example is U.S. Pat. No. 4,655,777 (Dunn et al.) which describes a method of producing biodegradable protheses comprising a composite of resorbable fibers reinforcing a biodegradable polymer matrix and the use thereof in medical applications. These filled polymers have as a limitation the number of intricate shapes which can be fabricated therefrom.